yii database host check

How can I check whether database host is valid?

  try {
     Yii::app()->db;
  } catch (Exception $ex) {
     echo $ex->getMessage();
  }

Code above gives me this error when I use invalid host address:

PDO::__construct(): php_network_getaddresses: getaddrinfo failed: No such host is known.

I just want to receive something that returns false, so I could display my own error message